Cooling system for electronics with improved thermal interface

ABSTRACT

A heat pipe system including a heat transfer block and a heat pipe coupled to the heat transfer block by a clip. By utilizing a clip to couple the heat pipe to the heat transfer block, a higher degree of thermal coupling may be achieved, thereby allowing more heat to be transferred from the heat transfer block to the heat pipe. The heat pipe system has particular application in transferring heat away from heat-producing electronic components, such as computer chips.

FIELD OF THE INVENTION

[0001] The present invention relates to a method and apparatus for aheat pipe system for removing heat from electronic equipment, and inparticular, a heat pipe system for removing heat from a laptop computer.

DESCRIPTION OF THE RELATED ART

[0002] A basic heat pipe comprises a closed or sealed envelope or achamber containing an isotropic liquid-transporting wick and a workingfluid capable of having both a liquid phase and a vapor phase within adesired range of operating temperatures. When one portion of the chamberis exposed to relatively high temperature it functions as an evaporatorsection. The working fluid is vaporized in the evaporator sectioncausing a slight pressure increase forcing the vapor to a relativelylower temperature section of the chamber defined as a condenser section.The vapor is condensed in the condenser section and returned through theliquid-transporting wick to the evaporator section by capillary pumpingaction.

[0003] Because it operates on the principle of phase changes rather thanon the principles of conduction or convection, a heat pipe istheoretically capable of transferring heat at a much higher rate thanconventional heat transfer systems. Consequently, heat pipes have beenutilized to cool various types of high heat-producing apparatus, such aselectronic equipment (See, e.g., U.S. Pat. Nos. 5,884,693, 5,890,371,and 6,076,595).

[0004] Heat pipe assemblies are often used to remove heat from theCentral Processing Unit (CPU) and other high power chips in computers.Maintenance of a good contact between the CPU (or other chip) and theheat pipe assembly is essential for insuring good overall heat transfer.

[0005] Some conventional heat pipe assemblies create a contact betweenthe CPU (or other chip) and a portion of the heat pipe through a heattransfer plate. Such heat transfer plates are disposed either above orbelow the CPU or chip, and are typically centered on the CPU or chip byguide members on the heat transfer plate which interface with guidemembers on the CPU or chip.

[0006] Most conventional heat transfer plates comprises metal blockswith at least one tunnel or recess therein for receiving a flattened endof the associated heat pipe. FIG. 1 shows such a conventional heat pipesystem 200. The heat pipe system 200 includes a heat transfer block 210,a heat pipe 220, and a heat dissipation structure 230. In a typicalenvironment, such heat pipe system 200 would be disposed in proximity toa heat-producing apparatus (e.g. CPU, chip, etc.), such that the heattransfer block 210 would be in direct contact with the heat-producingapparatus. The heat transfer block 210 includes a tunnel 211 therein forreceiving a flattened portion 221 of the heat pipe 220. The heat pipe220 also includes a crimped end or ‘pinchoff’ portion 222 disposed atone end of the flattened portion 221. An end of the heat pipe 220opposite the flattened portion 221 is coupled to the heat dissipationstructure 230 (e.g., fin block). During manufacture of the heat pipesystem shown in FIG. 1, the flattened portion 221 of the heat pipe 220is inserted into the tunnel 211 in the heat transfer block 210, and issecured therein.

[0007] Since this tunnel 211 in the heat transfer block 210 must be madelarge enough to receive the flattened end 221 of the heat pipe 220, andthe pinchoff portion 222 of the heat pipe, the tunnel must be made atleast as wide as the pinchoff. Since the pinchoff 222 is almost alwayswider than the flattened portion 221 of the heat pipe 220, the flattenedportion of the heat pipe does not fit snugly in the tunnel 211, andthus, a poor heat contact is created between the flattened portion ofthe heat pipe and the heat transfer block 210. Due to the poor heatcontact between the flattened portion of the heat pipe 220 and the heattransfer block 210, maximum heat cannot be transferred from the CPU orchip to the heat pipe through the heat transfer plate.

[0008] Therefore, there is currently a need for a heat pipe system foreffectively transferring maximum heat from a CPU (or other chip) to aheat pipe assembly in a computer.

SUMMARY OF THE INVENTION

[0009] The present invention is a heat pipe system including a heattransfer block and a heat pipe coupled to the heat transfer block by aclip.

[0010] The above and other advantages and features of the presentinvention will be better understood from the following detaileddescription of the exemplary embodiments of the invention which isprovided in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a perspective view showing a conventional heat pipesystem.

[0012]FIG. 2 is a perspective view showing a heat pipe system accordingto a first exemplary embodiment of the present invention.

[0013]FIG. 3 is a perspective view showing a magnified version of theheat pipe system shown in FIG. 2.

[0014]FIG. 4 is a perspective view showing an exploded and magnifiedversion of the heat pipe system shown in FIG. 2.

[0015]FIG. 5 is a perspective view showing a heat pipe system accordingto a second exemplary embodiment of the present invention.

[0016]FIG. 6 is a perspective view showing an exploded version of theheat pipe system shown in FIG. 5.

[0017]FIG. 7 is a perspective view showing a heat pipe system accordingto a third exemplary embodiment of the present invention.

[0018]FIG. 8 is a perspective view showing an enlarged of the heat pipesystem shown in FIG. 7.

DETAILED DESCRIPTION

[0019] The present invention comprises an improved apparatus and methodfor transferring heat from a heat-producing electronic equipment (e.g.,CPU or other computer chip) to a heat pipe through the use of a heattransfer plate. By attaching the heat pipe to the heat transfer platethrough a clip placed in the center of the heat transfer plate, maximumheat transfer from the heat transfer plate to the heat pipe can beachieved.

[0020] Referring to FIG. 2, there is shown a heat pipe system 100according to a first exemplary embodiment of the present invention. Theheat pipe system 100 comprises a heat transfer block 110, a heat pipe120, and a heat dissipation structure 130.

[0021] The heat transfer block 110 includes a channel 111 therein forreceiving a flattened portion 121 of the heat pipe 120. The heat pipe120 also includes a pinchoff portion 122 disposed at one end of theflattened portion 121. An end of the heat pipe 120 opposite theflattened portion 121 is coupled to the heat dissipation structure 130(e.g., fin block). One end of the channel 111 of the heat transfer block110 has a flared portion 112 for receiving the pinchoff portion 122 ofthe heat pipe 120. A clip member 140 overlies and secures the flattenedportion 121 of the heat pipe 120 in the channel 111. It will be notedthat the clip member 140 includes a main surface 141, and two sidesurfaces 142, 143 disposed orthogonal to the main surface. The mainsurface 141 primarily overlies the flattened portion 121 of the heatpipe 120, and the two side surfaces 142, 143 primarily reside in clipchannels 113, when the clip 140 is coupled to the heat transfer block110.

[0022]FIG. 3 shows an enlarged view of the heat pipe 120 and heattransfer block 110 of the heat pipe system 100 according to the firstexemplary embodiment of the present invention. It will be noted that theflattened portion 121 of the heat pipe is secured in the channel 111 ofthe heat transfer block 110 by the clip member 140.

[0023]FIG. 3 explicitly shows that the two side surfaces 142, 143 of theclip are received in clip channels 113 formed in the heat transfer block110. It will be noted that although the clip channels 113 are formed aschannels of a specific length which is less then the length of thetransfer block 110, the clip channels may also be formed as full-lengthchannels, such as channel 111. As will be understood by those skilled inthe art, forming the clip channels 113 as full-length channels mayreduce the expense of producing the heat transfer block 110 by allowingthe transfer block to be formed completely by extrusion processes. Theflattened portion 121 of the heat pipe 120 and the clip 140 may besecured in the channel 111 and the clip channels 113 respectively byfasteners (e.g., screws, bolts, stakes, rivets, etc.), solder, epoxy orother known materials.

[0024] Alternatively, the flattened portion 121 of the heat pipe 120 andthe clip 140 may be secured in the channel 111 and the clip channels 113by the surface friction of the flattened portion and the clip 140against the walls of the channel 111 and the clip channels 113. In orderto accomplish a tight friction contact between the channel 111 and theflattened portion 121 of the heat pipe 120, the channel is made onlyslightly wider than the flattened portion, so that the flattened portionfits snugly in the channels. To effect a tight friction contact betweenthe clip 140 and the clip channels 113, the side surfaces 142, 143 ofthe clip are splayed out (i.e., away from the main surface) slightly, sothat the side surfaces of the clip are urged against the clip channelwalls when the clip is disposed in the heat transfer block 110.

[0025] The heat transfer block 110 also includes guide members 114 withopenings 115 formed therein for securing the heat transfer block to aCPU or chip. Typically, a CPU or chip will include complementary guidemembers, such as posts, which may be received in the openings 115 inorder to secure the heat transfer block 110 to the CPU or chip.

[0026] The above-described heat pipe system 100 may be formed by variousmethods. For example, the heat transfer block 110 may be formed as asingle substantially uniform part which is later milled to create theheat pipe channel 111 and clip channels 113. Once the milled part hasbeen manufactured, the heat pipe 120 and clip 140 may be bonded to theheat transfer block 110 by the methods discussed above (e.g., solder,epoxy, friction, fasteners), or by other means known to those skilled inthe art. Alternatively, the heat transfer block 110 may be formed withthe heat pipe channel 111 and the clip channels 113 already formedtherein, by a process such as extrusion.

[0027] Since, in the present invention, the flattened portion 121 of theheat pipe 120 fits tightly within the channel 111 in the heat transferblock 110, and is further secured using clip 140, maximum heat transferfrom the heat transfer block to the heat pipe can be achieved. Asexplained above, in conventional heat pipe systems such maximum heattransfer could not be realized due to the fact that the flattenedportion of the heat pipe did not fit snugly within the channel (See FIG.1). Thus, the present invention it is submitted that the presentinvention represents a significant advance in heat transfer technology.

[0028]FIG. 4 shows an enlarged and exploded view of the heat pipe 120and heat transfer block 110 of the heat pipe system 100 according to thefirst exemplary embodiment of the present invention. FIG. 4 clearlyshows that the channel 111 includes a flared portion 112 which is widerthan the rest of the channel. As stated above, this flared portion 112operates to receive the pinchoff portion 122 of the heat pipe 120. FIG.4 also clearly shows the clip channels 113. Although the clip channels113 are oval-shaped in FIG. 4, it will be understood that these channelsmay take various geometrical shapes (e.g., rectangles, etc.).

[0029] One of the main reasons for utilizing the channel structure 111described above is to provide a means of applying downward pressure onthe heat transfer block 110. The downward pressure must be applied atthe physical center of the CPU or chip to which the transfer block 110is coupled to assure that the transfer block is seated squarely on theCPU or chip without creating a gap therebetween. Often times when thetransfer block 110 is not seated squarely on the CPU or chip awedge-shaped gap is formed between the transfer block and the CPU orchip. Such a gap could result in poor thermal contact between the CPU orchip and the transfer block 110, and could, in the case of a CPU havingan exposed silicon die, cause cracking or splaying from the edges of thedie, and subsequently reduce heat transfer area or cause electricalmalfunction. The downward pressure cannot be applied through the wall ofthe heat pipe because the wall is often made of a thin metal (e.g.,Copper) sheet which does not have sufficient tensile strength totransfer the force without deformation of the metal. Such deformationmay result in diminution of the contact pressure, and reduction in heatpipe performance due to the local reduction in vapor flow area. Thechannel structure 111 is designed to circumvent the deformation problem,while allowing pressure to be applied at the center of the CPU or chipto which the transfer block 110 is coupled.

[0030] Additionally, in the first exemplary embodiment described above,the heat pipe 120 is disposed at the physical center of the CPU or chip,the region of maximum heat production. Location of the heat pipe 120 inthis region produces a heat pipe system 100 with a low thermalresistance.

[0031] Referring to FIG. 5, there is shown a heat pipe system 300according to a second exemplary embodiment of the present invention.Similar to the heat pipe system 100, the heat pipe system 300 includes aheat transfer block 310, a heat pipe 320, and a heat dissipationstructure (not shown). However, the heat pipe system 300 includes only asingle clip channel 313 for receiving a clip 340.

[0032]FIG. 5 shows that the heat transfer block 310 includes a channel311 therein for receiving a flattened portion 321 of the heat pipe 320.The heat pipe 320 also includes a pinchoff portion 322 disposed at oneend of the flattened portion 321. An end of the heat pipe 320 oppositethe flattened portion 321 is coupled to the heat dissipation structure(not shown). One end of the channel 311 of the heat transfer block 310has a flared portion 312 for receiving the pinchoff portion 322 of theheat pipe 320. A clip member 340 overlies and secures the flattenedportion 321 of the heat pipe 320 in the channel 311. It will be notedthat the clip member 340 includes a main surface 341, and two sidesurfaces 342, 343 disposed orthogonal to the main surface. The mainsurface 341 primarily overlies the flattened portion 321 of the heatpipe 320, and the two side surfaces 342, 343 primarily reside in singleclip channel 313, when the clip 340 is coupled to the heat transferblock 310.

[0033] It will be noted that the two side surfaces 342, 343 of the clipare received in a single clip channel 313 formed in the heat transferblock 310. The flattened portion 321 of the heat pipe 320 and the clip340 may be secured in the channel 311 and the single clip channel 313respectively by fasteners (e.g., screws, bolts, etc.), solder, epoxy orother known materials.

[0034] Alternatively, the flattened portion 321 of the heat pipe 320 andthe clip 340 may be secured in the channel 311 and the single clipchannel 313 by the surface friction of the flattened portion and theclip 340 against the walls of the channel 311 and the single clipchannel 313. As stated above with respect to the first exemplaryembodiment, in order to accomplish a tight friction contact between thechannel 311 and the flattened portion 321 of the heat pipe 320, thechannel is made only slightly wider than the flattened portion, so thatthe flattened portion fits snugly in the channels. To effect a tightfriction contact between the clip 340 and the single clip channel 313,the side surfaces 342, 343 of the clip are splayed out (i.e., away fromthe main surface) slightly, so that the side surfaces of the clip areurged against the clip channel walls when the clip is disposed in theheat transfer block 310.

[0035] The heat transfer block 310 also includes guide members 314 withopenings 315 formed therein for securing the heat transfer block to aCPU or chip. Typically, a CPU or chip will include complementary guidemembers, such as posts, which may be received in the openings 315 inorder to secure the heat transfer block 310 to the CPU or chip.

[0036] As described above with reference to the heat pipe system 100 ofthe first exemplary embodiment, the heat pipe system 300 may be formedby various means such as milling and extrusion.

[0037] Referring to FIGS. 7 and 8, there is shown a heat pipe system 400according to a second exemplary embodiment of the present invention.Similar to the heat pipe system 100, the heat pipe system 400 includes aheat transfer block 410, a heat pipe 420, and a heat dissipationstructure 430. However, the heat pipe system 400 includes a flattenedclip member 440 which extends across the heat transfer block 410 withtabs 441, 442 formed therein for being received in respective channels451, 452 of the heat transfer block (See FIG. 8).

[0038]FIG. 7 shows that the heat transfer block includes a channel 411therein for receiving a flattened portion 421 of the heat pipe 420. Aclip member 440 overlies and secures the flattened portion 421 of theheat pipe 420 in the channel 411. It will be noted that the clip member440 includes a top surface 445, and a bottom surface 446 with tabs 441,442 extending orthogonally therefrom (See FIG. 8).

[0039] The flattened portion 421 of the heat pipe 420 and the clip 440may be secured in the channel 411 and the clip channels 451, 452respectively by fasteners (e.g., screws, bolts, etc.), solder, epoxy orother known materials.

[0040] Alternatively, the flattened portion 421 of the heat pipe 420 andthe clip 440 may be secured in the channel 411 and the clip channels451, 452 by the surface friction of the flattened portion and the clip440 against the walls of the channel 411 and the clip channels 451, 452.As stated above with respect to the first exemplary embodiment, in orderto accomplish a tight friction contact between the channel 411 and theflattened portion 421 of the heat pipe 420, the channel is made onlyslightly wider than the flattened portion, so that the flattened portionfits snugly in the channels. Similarly, to effect a tight frictioncontact between the clip 440 and the clip channels 451, 452, thechannels are made only slightly wider than the respective tabs 441, 442.

[0041] The heat transfer block 410 also includes guide members 414 withopenings 415 formed therein for securing the heat transfer block to aCPU or chip. Typically, a CPU or chip will include complementary guidemembers, such as posts, which may be received in the openings 415 inorder to secure the heat transfer block 410 to the CPU or chip.

[0042] As described above with reference to the heat pipe system 100 ofthe first exemplary embodiment, the heat pipe system 400 may be formedby various means such as milling and extrusion.

[0043] Although the invention has been described in terms of exemplaryembodiments, it is not limited thereto. Rather, the appended claimsshould be construed broadly, to include other variants and embodimentsof the invention which may be made by those skilled in the art withoutdeparting from the scope and range of equivalents of the invention.

What is claimed is:
 1. A heat pipe system comprising: a heat transferblock; and, a heat pipe coupled to the heat transfer block by a clip. 2.The heat pipe system of claim 1, wherein the clip includes a mainsurface and two side surfaces disposed substantially orthogonal to themain surface.
 3. The heat pipe system of claim 1, wherein the heattransfer block includes at least one clip channel disposed therein forreceiving the clip.
 4. The heat pipe system of claim 1, wherein the heattransfer block includes at least two clip channels disposed therein forreceiving the clip.
 5. The heat pipe system of claim 1, wherein the heattransfer block includes at least one heat pipe channel disposed thereinfor receiving the heat pipe.
 6. The heat pipe system of claim 5, whereinthe heat pipe includes a main portion and a pinchoff portion, whereinthe pinchoff portion is disposed in the heat pipe channel.
 7. The heatpipe system of claim 5, wherein the heat pipe is coupled to the heatpipe channel by solder.
 8. The heat pipe system of claim 5, wherein theheat pipe is coupled to the heat pipe channel by epoxy.
 9. The heat pipesystem of claim 5, wherein the heat pipe is coupled to the heat pipechannel by friction.
 10. The heat pipe system of claim 5, wherein theheat pipe is coupled to the heat pipe channel by at least one fastener.11. The heat pipe system of claim 2, wherein the heat transfer blockincludes at least one clip channel disposed therein for receiving theclip, such that the two side surfaces of the clip are disposed in the atleast one clip channel.
 12. The heat pipe system of claim 11, whereinthe clip is coupled to the at least two clip channels by solder.
 13. Theheat pipe system of claim 11, wherein the clip is coupled to the atleast two clip channels by epoxy.
 14. The heat pipe system of claim 11,wherein the clip is coupled to the at least two clip channels byfriction.
 15. The heat pipe system of claim 11, wherein the heat pipe iscoupled to the heat pipe channel by at least one fastener.
 16. The heatpipe system of claim 2, wherein the heat transfer block includes atleast two clip channels disposed therein for receiving the clip, suchthat the two side surfaces of the clip are disposed in the at least twoclip channels.
 17. The heat pipe system of claim 16, wherein the clip iscoupled to the at least two clip channels by solder.
 18. The heat pipesystem of claim 16, wherein the clip is coupled to the at least two clipchannels by epoxy.
 19. The heat pipe system of claim 16, wherein theclip is coupled to the at least two clip channels by friction.
 20. Theheat pipe system of claim 16, wherein the heat pipe is coupled to theheat pipe channel by at least one fastener.
 21. The heat pipe system ofclaim 1, wherein the clip includes a top surface and bottom surface withat least two tabs extending orthogonally from the bottom surface. 22.The heat pipe system of claim 21, wherein the heat transfer blockincludes at least two channels for receiving the at least two tabs inthe clip.
 23. The heat pipe system of claim 1, wherein the clip extendssubstantially across an entire top surface of the heat transfer block.24. A computer comprising: at least one electronic component; a heattransfer block disposed adjacent to the at least one electroniccomponent; and, a heat pipe coupled to the heat transfer block by aclip.
 25. A method for cooling a heat-producing element, comprising thesteps of: disposing a heat transfer block adjacent the heat-producingelement; coupling the heat transfer block to a heat pipe using a clip.26. A method for manufacturing a heat pipe assembly, comprising thesteps of: forming a heat transfer block with at least one heat pipechannel and at least one clip channel disposed therein; bonding a heatpipe to the heat pipe channel; and bonding a clip to the at least oneclip channel, such that the clip overlies at least a portion of the heatpipe.
 27. The method of claim 26, wherein the steps of bonding the heatpipe and bonding the clip comprise bonding by solder.
 28. The method ofclaim 26, wherein the steps of bonding the heat pipe and bonding theclip comprise bonding by epoxy.
 29. The method of claim 26, wherein thesteps of bonding the heat pipe and bonding the clip comprise bonding byfasteners.